The electrodes of spot welding machines used in automotive manufacture are usually constructed of copper or an alloy thereof and have tips which are rounded or which are frusto-conical in shape. During use, these tips become deformed or distorted and contaminated with oxides or other foreign materials. Such deformation or contamination often interferes with or reduces the electrical conductivity of the tip, and results in welds which are weak.
The welding machines used on production lines, particularly in the automotive industry, have a plurality of welding tips which are brought into position simultaneously as the object to be welded progresses through the line. Sometimes such machines may have a dozen or more such tips, all of which need to be periodically dressed or reshaped after extended use. In the past, the malformed or contaminated tips were merely replaced when they began to produce bad welds. Later, it was found that they could be revitalized by cleaning and/or reshaping. Several patent disclosures demonstrate tools devised for this purpose. U.S. Pat. No. 3,820,437, British Patent No. 524,348 and E.P. No. 87-685-A each discloses a power-driven dressing tool to restore a welding tip to its original shape by grinding off the foreign materials or removing some of the metal until the desired configuration is achieved. Such dressing tools obviously have been used for many years. The difficulty in employing them on welding machines having multiple electrode welding tips, has been the application of sufficient pressure of the tool against the tip so that each tip can be quickly and easily restored. On such welding machines, the electrodes often are merely suspended by a flexible means from a framework so as to prevent the operator holding the dressing tool from applying sufficient pressure to carry out the process easily or quickly. The practice noted by the present inventors has been for one person to hold and operate the dressing tool while one or two others apply pressure to hold the tool against the welding tip, sometimes using a timber, to obtain the requisite pressure.